The gill bearing fungi are known under the family _Agaricaceæ_, or popularly the agarics. They are distinguished by the fruiting area being distributed over the surface of plate-like or knife-like extensions or folds, usually from the under surface of the cap. These are known as the gills, or lamellæ, and they usually radiate from a common point, as from or near the stem, when the stem is present; or from the point of attachment of the pileus when the stem is absent. The plants vary widely in form and consistency, some being very soft and soon decaying, others turning into an inky fluid, others being tough and leathery, and some more or less woody or corky. The spores when seen in mass possess certain colors, white, rosy, brown or purple brown, black or ochraceous. While a more natural division of the agarics can be made on the basis of structure and consistency, the treatment here followed is based on the color of the spores, the method in vogue with the older botanists. While this method is more artificial, it is believed to be better for the beginner, especially for a popular treatment. The sections will be treated in the following order: 1. The purple-brown-spored agarics. 2. The black-spored agarics. 3. The white-spored agarics. 4. The rosy-spored agarics. 5. The ochre-spored agarics. FOOTNOTES: [A] For analytical keys to the families and genera see Chapter XXIV. CHAPTER IV. THE PURPLE-BROWN-SPORED AGARICS.[B] The members of this subdivision are recognized at maturity by the purple-brown, dark brown or nearly black spores when seen in mass. As they ripen on the surface of the gills the large number give the characteristic color to the lamellæ. Even on the gills the purple tinge of the brown spores can often be seen. The color is more satisfactorily obtained when the spores are caught in mass by placing the cap, gills downward, on white paper. AGARICUS Linn. (PSALLIOTA Fr.) In the genus _Agaricus_ the spores at maturity are either purple-brown in mass or blackish with a purple tinge. The annulus is present on the stem, though disappearing soon in some species, and the stem is easily separated from the substance of the pileus. The gills are free from the stem, or only slightly adnexed. The genus is closely related to _Stropharia_ and the species of the two genera are by some united under one genus (_Psalliota_, Hennings). Peck, 36th Report, N. Y. State Mus., p. 41--49, describes 7 species. Lloyd Mycol. Notes, No. 4, describes 8 species. C. O. Smith, Rhodora, I: 161--164, 1899, describes 8 species.